Kein solcher Spaltenfehler in Android Studio

Question

Ich bin ein Anfänger/Student, der an einem App-Projekt arbeitet, das eine Todo-Liste anzeigen wird. Ich habe Warndialoge verwendet, um Eingaben vom Benutzer zu erhalten und letztere in einer Tabelle zu speichern. Wenn ich in zwei Dialoge erweitert sowohl Informationen über die Aufgabe zu bekommen und das Thema, trat der folgende Fehler:

E/AndroidRuntime: FATAL EXCEPTION: main 
       Process: com.example.zilunlin.bacpack, PID: 8118 
       java.lang.RuntimeException: Unable to start activity ComponentInfo{com.example.zilunlin.bacpack/com.example.zilunlin.bacpack.MainActivity}: android.database.sqlite.SQLiteException: no such column: subject (code 1): , while compiling: SELECT _id, title, subject FROM tasks 
       ################################################################# 
       Error Code : 1 (SQLITE_ERROR) 
       Caused By : SQL(query) error or missing database. 
       (no such column: subject (code 1): , while compiling: SELECT _id, title, subject FROM tasks) 
       ################################################################# 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3254) 
        at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:3350) 
        at android.app.ActivityThread.access$1100(ActivityThread.java:222) 
        at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1795) 
        at android.os.Handler.dispatchMessage(Handler.java:102) 
        at android.os.Looper.loop(Looper.java:158) 
        at android.app.ActivityThread.main(ActivityThread.java:7229) 
        at java.lang.reflect.Method.invoke(Native Method) 
        at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:1230) 
        at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:1120) 
       Caused by: android.database.sqlite.SQLiteException: no such column: subject (code 1): , while compiling: SELECT _id, title, subject FROM tasks 
       ################################################################# 
       Error Code : 1 (SQLITE_ERROR) 
       Caused By : SQL(query) error or missing database. 
       (no such column: subject (code 1): , while compiling: SELECT _id, title, subject FROM tasks) 
       ################################################################# 
        at android.database.sqlite.SQLiteConnection.nativePrepareStatement(Native Method) 
        at android.database.sqlite.SQLiteConnection.acquirePreparedStatement(SQLiteConnection.java:1058) 
        at android.database.sqlite.SQLiteConnection.prepare(SQLiteConnection.java:623) 
        at android.database.sqlite.SQLiteSession.prepare(SQLiteSession.java:588) 
        at android.database.sqlite.SQLiteProgram.<init>(SQLiteProgram.java:59) 
        at android.database.sqlite.SQLiteQuery.<init>(SQLiteQuery.java:37) 
        at android.database.sqlite.SQLiteDirectCursorDriver.query(SQLiteDirectCursorDriver.java:44) 
        at android.database.sqlite.SQLiteDatabase.rawQueryWithFactory(SQLiteDatabase.java:1454) 
        at android.database.sqlite.SQLiteDatabase.queryWithFactory(SQLiteDatabase.java:1301) 
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1172) 
        at android.database.sqlite.SQLiteDatabase.query(SQLiteDatabase.java:1340) 
        at com.example.zilunlin.bacpack.MainActivity.updateUI(MainActivity.java:128) 
        at com.example.zilunlin.bacpack.MainActivity.onCreate(MainActivity.java:36) 
        at android.app.Activity.performCreate(Activity.java:6876) 
        at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1135) 
        at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:3207) 
        ... 9 more 

Beachten Sie, dass dieser Fehler nicht direkt erkannt und ist nur sichtbar, wenn ich das Debuggen auszuführen.

Das folgende ist mein Code von MainActivity, insbesondere die Dialoge

@Override 
public boolean onOptionsItemSelected(MenuItem item) { 
    switch (item.getItemId()) { 
     case R.id.action_add_task: 
      final EditText taskEditText = new EditText(this); 
      AlertDialog dialog = new AlertDialog.Builder(this) 
        .setTitle("Add a new task") 
        .setMessage("What is it that you gotta do?") 
        .setView(taskEditText) 
        .setPositiveButton("Add", new DialogInterface.OnClickListener() { 
         @Override 
         public void onClick(DialogInterface dialog, int which) { 
          String task = String.valueOf(taskEditText.getText()); 
          SQLiteDatabase db = mHelper.getWritableDatabase(); 
          ContentValues values = new ContentValues(); 
          values.put(TaskContract.TaskEntry.COL_TASK_TITLE, task); 
          db.insertWithOnConflict(TaskContract.TaskEntry.TABLE, 
            null, 
            values, 
            SQLiteDatabase.CONFLICT_REPLACE); 
          db.close(); 
          updateUI(); 
         } 
        }) 
        .setNegativeButton("Cancel", null) 
        .create(); 
      dialog.show(); 
      final EditText SubjectText = new EditText(this); 
      AlertDialog setSubject = new AlertDialog.Builder(this) 
        .setTitle("Add its subject") 
        .setMessage("What is its subject?") 
        .setView(SubjectText) 
        .setPositiveButton("Add", new DialogInterface.OnClickListener() { 
         @Override 
         public void onClick(DialogInterface setSubject, int which) { 
          String subject = String.valueOf(SubjectText.getText()); 
          SQLiteDatabase db = mHelper.getWritableDatabase(); 
          ContentValues subjectvalues = new ContentValues(); 
          subjectvalues.put(TaskContract.TaskEntry.SUBJECT_NAME, subject); 
          db.insertWithOnConflict(TaskContract.TaskEntry.TABLE, 
            null, 
            subjectvalues, 
            SQLiteDatabase.CONFLICT_REPLACE); 
          db.close(); 
          updateUI(); 
         } 

        }) 
        .setNegativeButton("Cancel", null) 
        .create(); 
      setSubject.show(); 




      return true; 

     default: 
      return super.onOptionsItemSelected(item); 
    }} 

Hier ist der db Vertrag

import android.provider.BaseColumns; 

public class TaskContract { 
    public static final String DB_NAME = "com.zilunlin.todolist.db"; 
    public static final int DB_VERSION = 1; 

    public class TaskEntry implements BaseColumns { 
     public static final String TABLE = "tasks"; 
     public static final String COL_TASK_TITLE = "title"; 
     public static final String SUBJECT_NAME = "subject"; 
    } 
} 

und schließlich, hier ist der db Helfer

public class TaskDbHelper extends SQLiteOpenHelper { 

    public TaskDbHelper(Context context) { 
     super(context, TaskContract.DB_NAME, null, TaskContract.DB_VERSION); 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) { 
     String createTable = "CREATE TABLE " + TaskContract.TaskEntry.TABLE + " (" + 
       TaskContract.TaskEntry._ID + " INTEGER PRIMARY KEY AUTOINCREMENT, " + 
       TaskContract.TaskEntry.COL_TASK_TITLE + " TEXT NOT NULL);" + 
       TaskContract.TaskEntry.SUBJECT_NAME + " TEXT NOT NULL);"; 

     db.execSQL(createTable); 
    } 

    @Override 
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) { 
     db.execSQL("DROP TABLE IF EXISTS " + TaskContract.TaskEntry.TABLE); 
     onCreate(db); 
    } 
} 

Ich verstehe, dass diese Frage vielleicht dupliziert wird, aber mit meinem derzeitigen Verständnis von Programmierung, ich Ich bin nicht in der Lage, die Antworten angemessen zu übertragen. Jede Antwort wird sehr geschätzt.

PS: Ich folgte Aldo Ziflajs hilfreiches Tutorial zu Todo-Listen.

Answer 1

Sie zusätzliche Semikolon hinzugefügt haben ...

Changed diese

String create = "CREATE TABLE IF NOT EXISTS" + TaskContract.TaskEntry.TABLE + "(" + TaskContract.TaskEntry._ID + "INTEGER PRIMARY KEY AUTOINCREMENT", + TaskContract.TaskEntry.COL_TASK_TITLE + "TEXT NICHT NULL", + TaskContract.TaskEntry.SUBJECT_NAME + "TEXT NOT NULL)";